I would like to suggest a commercial solution like TGZ to PST Converter Software. This tool export TGZ items like emails, contacts, journals, notes, etc. This app import TGZ to PST and various file formats including EML, MSG, EMLX, vCard, vCal, etc.
Read more: https://www.kdetools.com/blog/how-to-import-tgz-to-pst.html
